1. Technical Field
The present disclosure relates to a hybrid power supply system. More specifically, relates to a system including lithium ion batteries and fuel cells.
2. Description of Related Art
A hybrid power supply system includes a fuel cell pack with a plurality of fuel cells connected in series and a lithium-ion battery pack with a plurality of lithium ion batteries connected in series. The fuel cell pack may be used to charge the whole lithium ion battery pack. More specifically, the fuel cell pack charges each of lithium ion batteries at the same time. However, performances of the lithium ion batteries may be different because of fabrication errors. An inconformity of charging and discharging between the lithium ion batteries may occur from these different performances. One lithium ion battery may be over charged or over discharged, which will influence the safety, charging and discharging capacity, and life span of the whole lithium ion battery pack.
Battery management systems are always used to regulate the charging and discharging inconformity between the lithium ion batteries in the pack connected in series. However, this way of regulating has a relatively low effective utilization of the electrical quantity of the lithium ion battery pack. In addition, these battery management systems have complex regulating circuits used for regulating the inconformity between lithium ion batteries in the pack. Therefore, the cost of a hybrid power supply system cannot be lowered.
What is needed, therefore, is to provide a hybrid power supply system with a relatively long cycle life and a low cost.